The innocuousness of adiabatic instabilities in coupled scalar field-dark matter models

TL;DR

This paper reviews how adiabatic solutions in coupled scalar field-dark matter models suppress large-scale instabilities, and presents preliminary data analysis indicating such models can be consistent with cosmological observations.

Contribution

It demonstrates that adiabatic solutions in coupled models mitigate instabilities and shows these models can fit observational data, offering a viable alternative in cosmology.

Findings

Adiabatic solutions suppress large-scale instabilities.

Coupled models with gravitational strength coupling fit observational data.

Preliminary likelihood analysis supports viability of these models.

Abstract

Non-minimally coupled scalar field models suffer of unstable growing modes at the linear perturbation level. The nature of these instabilities depends on the dynamical state of the scalar field. In particular in systems which admit adiabatic solutions, large scale instabilities are suppressed by the slow-roll dynamics of the field. Here we review these results and present a preliminary likelihood data analysis suggesting that along adiabatic solutions coupled models with coupling of order of gravitational strength can provide viable cosmological scenarios satisfying constraints from SN Ia, CMB and large scale structure data.